The overall purpose of this proposal is to obtain support for a Centralized Facility for Protein Sequencing. Specifically, support is sought for a Gas-Phase Sequencer to be used in such applications as: sequence location of affinity labeled amino acids in enzymes, complete sequencing of M-Components used in x-ray diffraction studies, comparative sequencing of pre- and post-processed proteins, N-terminal sequencing of cell free translation products to both verify DNA sequences and provide reading frame adjustments, and identification of protein sequences from gene fusion phenomenon, of point mutation sites from site-directed mutagenesis experiments, and of incorporation positions of useful NMR probes such as fluorinated amino acids. Coupled with the already available Centralized Amino Acid Analyzer Facility, the protein sequencer will provide the essential element to create a complete protein primary structure facility.